Windows only: IndexYourFiles is a lightweight and completely portable file-indexer that leaves behind no trace and requires nothing more than the executable.

After unzipping the application, all you need to do is run it and give a folder, local drive, or network drive to begin indexing. You can save profiles from within the program allowing you to keep a separate index for home, work, or even individual drives to limit your searches to drives you use for the task at hand. Indexing is snappy, as is the search engine itself. During my test run it indexed 110GB of data in a matter of seconds. If you're in a position where you can't install a desktop search engine at work but would benefit from using one, IndexYourFiles is a stealthy option. For another portable-friendly file indexer, check out Locate32. Thanks Joelena!